1. Field of the Invention
The present invention relates to a head-protecting airbag device whose airbag is mountable on an upper periphery of a window of a vehicle in a folded-up configuration with an upper edge thereof secured to a vehicle body structure and is deployable downward over the window when fed with an inflation gas.
2. Description of Related Art
JP 2012-214114 A discloses a known head-protecting airbag device. In this head-protecting airbag device, an airbag includes a main chamber that is deployable over a window at an inboard side of a vehicle and a regulating portion that extends straightly rear- and upwardly inside the main chamber in order to regulate the thickness of the main chamber. The airbag further includes a sub chamber that has a rod-like shape. The sub chamber, which is arranged along the lower edge of the main chamber when the airbag is in a flattened state, is located on an outboard side of the regulating portion in an overlapping fashion, such that the thickness of the airbag is generally uniform as a whole when inflated.
In this known head-protecting device, the sub chamber is so arranged as to extend at a slant relative to an up and down direction on an outboard side of the main chamber. However, this sub chamber helps uniform the thickness of the airbag as a whole by covering an outboard side of the regulating portion which is formed by jointing two walls of the main chamber together, and does not help increase the thickness of the airbag as a whole. This configuration does not provide a sufficient arresting property in the event of a rollover crash of a vehicle. A rollover crash is not considered in this known head-protecting airbag devices, either.